Overview &
Objective(s): Determine relative
abundance, distribution, movements, and habitat use of manatees associated with
coastal waters and rivers from Marco Island through Whitewater Bay. Identify resources critical to manatees
in the region, including distribution and abundance of submerged aquatic
vegetation and locations of freshwater drinking sites. Develop an
individual-based ATLSS model to predict manatee response to changes in
hydrology achieved specifically by the Southern Golden Gate Estates (SGGE) project
and more broadly by the Comprehensive Everglades Restoration Plan. Additional
information on population trend, distribution, and habitat use, coupled with
models of hydrology, bathymetry, aquatic vegetation, and salinity, will allow
development of a population-level model capable of predicting their response to
future changes. This SGGE modeling
effort will provide invaluable information as a small-scale test case for
understanding and predicting how restoration efforts in the Everglades will
affect manatees.

The study supports the
Landscape-Scale Modeling (LSM; p. 80-81) by 1) providing an individual-based
demographic model of a threatened species, the West Indian manatee (p. 80), and
2) by providing landscape-scale monitoring and assessment for MAP (p. 81,
90).

Each manatee project task
addresses a number of USGS project tasks related to hydrology, habitats and
species, ecological indicators, and threatened and endangered species. Because
the manatee is a federally listed species, our work supports a variety of needs
identified by the DOI for listed species.

Status: On track for completion in FY05.

Recent Products:

Metadata reviewed, revised,
and posted to SOFIA

Presentations at the 15th
Biennial Conference on the Biology of Marine Mammalogy:

Brad Stith, Jim Reid, and
Susan Butler, 2003, Modeling manatee response to restoration in the Ten
Thousand Islands and Everglades National Park. Oral presentation at the 15th
Biennial Conference on the Biology of Marine Mammals, 15-19 December 2003,
Greensboro, North Carolina.

James P. Reid, Bradley M.
Stith, and Susan M. Butler, 2003, Florida manatees in the western Everglades:
Implications for restoration assessment. Oral presentation at the 15th Biennial
Conference on the Biology of Marine Mammals, 15-19 December 2003, Greensboro,
North Carolina.

Susan M. Butler, James P.
Reid, and Bradley M. Stith, 2003, Detailed movements and habitat use patterns
of radio tagged manatees in the western Everglades. Poster presentation at the
15th Biennial Conference on the Biology of Marine Mammals, 15-19 December 2003,
Greensboro, North Carolina. Available at http://cars.er.usgs.gov/posters/index.html#manatee

Planned Products:

Two presentations submitted
to the First National Conference on Ecosystem Restoration

The radio-tracking task provides data critical for
documenting the pre-restoration use of habitat by manatees within the region
affected by the SGGE restoration. These data are essential for validating
parameters in the individual-based model described in task 3. Satellite-based
Argos transmitters and Global Positioning System (GPS) tags have been used to
remotely track movements of 36 manatees; radio tracking efforts are
ongoing. Most manatees were
captured and radio-tagged during the winter months at Port of the Islands, Faka
Union canal, Collier County. Preliminary analysis of movement patterns suggest
that manatees in this region rely on existing freshwater sources, usually
traveling between offshore seagrass beds and these inshore freshwater sites
every 3-5 days. Individual movements are linked to a network of seagrass beds,
which is revealed by manatee locations during GPS tag deployments. Seven of the
manatees tracked in this study also traveled to areas more than 100 km north of
the Ten Thousand Islands. Most remained within the study area, however,
providing the first detailed movement data collected across seasons from wild
manatees in the region.

Work to be undertaken
during the proposal year and a description of the methods and procedures:

We have relied on two types of technologies to acquire geographic
locations from tagged manatees. Most tagged manatees are fitted with
satellite-based Argos transmitters, which provide approximately four location
fixes per 24-hour period, and have a serviceable battery life of six months.
Four newly developed Argos-linked GPS tags have been acquired and deployed in
FY03. This tag relays GPS locations as sensor data through the Argos satellite
link, enabling detailed tracking data to be acquired remotely. The GPS tag
provides locations which are much more accurate than the Argos data (approx. 30 mvs.>150 m) every 15-30 minutes, but the battery life expectancy is much
shorter (8 weeks vs. 6 months). In combination, the Argos data provides
region-wide, long-term coverage suitable for revealing general patterns of
habitat use, while the GPS data shows fine details of travel pathways and time
spent in specific areas. Location data are formatted in SAS for error checking,
analyses, and display in ArcView. Databases are correlated with temperature,
salinity, and tidal data collected throughout the region.

Further
descriptions of methods and procedures can be seen at the following web site:

Field efforts planned for
FY05 are minimal. Tagged manatees will be tracked through the end of the 2004
wet season. These individuals will then be utilized in the second year of a companion
study on the winter-use patterns of manatees in the TTI region. Tagged manatee
movement and environmental data collected between 2000 and 2004 from the study
area will be error-checked and formatted for analysis. This will enable further
development of the model efforts detailed in Task 2.

Remote and field-based
tracking has enabled documentation of manatee use patterns associated with near
shore habitats. These findings are relevant for determination of submerged
aquatic vegetation planned for the PBS project "Impacts of Hydrological
Restoration on Three Estuarine Communities of the Southwest Florida Coast and
on Associated Fauna" (Carol McIvor) http://sofia.usgs.gov/projects/impacts_est/. Collaboration with this project is planned to
establish baseline data on the patterns of distribution and abundance of
submerged aquatic vegetation in the TTI and ENP.

Distribution and movement
data on manatees, combined with water quality data obtained from monitoring
stations, will provide a basis for comparative studies in other areas within
the region. Sharing of tracking and model data, such as manatee high use areas
and travel patterns, are planned with TTI, ENP, and other agencies to address
resource management needs.

Specific Task
Product(s):

Open File Report - November
2004

Presentations submitted to
the First National Conference on Ecosystem Restoration - December 2004

We are developing a spatially-explicit,
individual-based ATLSS model for manatees to better understand how changes in
hydrology associated with restoration of SGGE and the Everglades may affect the
distribution and abundance of manatees. Telemetry data and aerial surveys have
demonstrated that manatees make regular use of many of the tidal rivers and
streams within the study area, primarily as a source of drinking water and as
thermal refugia during cold weather. To date, all 26 manatees we have analyzed
show a similar pattern of regular movement between near shore seagrass beds and
sources of freshwater up various rivers, creeks, and canals. Our task is to use
the telemetry data and water quality information to explain the movement
patterns of manatees, and to incorporate these insights into the
individual-based manatee model to properly simulate these movements and the
response of manatees to alterations in hydrology.

Work to be undertaken
during the proposal year and a description of the methods and procedures:

Work to
be undertaken includes four major tasks: 1) finalize the analysis of manatee
telemetry data obtained from Task 2 to support the development and
parameterization of the individual-based model, 2) develop empirically-based
surrogates for hydrology model output simulating the relationship between
salinity and freshwater inflow for major rivers, 3) finalize and validate the
individual-based manatee model, 4) devise and conduct a set of simulation runs
to evaluate different restoration scenarios.

The telemetry data analysis
task involves using GIS techniques to analyze the telemetry data and
characterize manatee behavior, including habitat use, movement patterns, time
budget, and home range size. We are using the telemetry data to delineate a
comprehensive network of sites used by manatees which will provide the
landscape used in all simulations.
The fine-scale GPS data is being used to develop detailed travel
corridors between offshore and inshore areas, as well as movement speeds for
incorporation into the model. The
coarse-scale Argos data is being used in a robust, multi-state mark-recapture
model to analyze the movement of manatees between different habitat zones (e.g.
riverine and offshore). This analysis provides transition probabilities as
input into the individual-based model in a Monte Carlo Markov Chain framework
to model the transition of manatees between different habitat zones, and to
provide a measure of individual heterogeneity in transition probabilities. We will complete the analysis of
manatee home ranges using a fixed kernal approach with least square cross
validation smoothing to identify overall home range, and core areas of utilization. Patterns of individual heterogeneity in
home range size and location will be incorporated into the model. We are using
a simple reinforcement model (Rescorla-Wagner) to model shifts in manatee home
ranges in response to changes in availability of freshwater. A sensitivity analysis will be
conducted to evaluate the parameters with the strongest influence on the
model. We will devise a set of
simple restoration scenarios that vary the influx of freshwater within the
network of river systems used by manatees. The "status quo" scenario will be used to output data from
the model to compare to the telemetry data (task 1) and to several years of
aerial survey data (completed for a previous task). The response of simulated manatees to several different
scenarios representing alternative restoration scenarios will be compared and
evaluated.

Because
no hydrology model is available for the estuarine or marine portions of this
study area, we will analyze data from monitoring stations within the study area
to develop empirical relationships between freshwater discharge and salinity
gradients at varying distances from point of discharge. We will vary these
empirical relationships to simulate output from a hydrology model under
alternative restoration scenarios. Water quality data will be obtained from
several sources, including the USGSPBS project "Southwest Florida Coastal and
Wetland Systems Monitoring Project" (E. Patino) (http://sofia.usgs.gov/projects/sys_monitor/).

Further
descriptions of methods and procedures can be seen at the following web sites: